KR20070086892A - Liquid precursor refill system - Google Patents

Abstract

Liquid precursor refill systems of the type typically used in the semiconductor industry. A remote precursor reservoir (210) and a secondary vapor delivery system (220) provide a CVD precursor to a local source. The local source contains a heat transfer means (310) and a local CVD precursor reservoir (320). A delivery line (400) connects this remote, secondary vapor delivery system and the local heat transfer means. During the constant or periodic operation, no liquid is present in the delivery line. The local CVD precursor reservoir may serve as an ampoule in a bubbler system, or may provide CVD precursor to an ampoule in a bubbler system.

Description

Liquid precursor refill device {LIQUID PRECURSOR REFILL SYSTEM}

BACKGROUND OF THE INVENTION The present invention relates generally to liquid precursor refill apparatus of the type used in the semiconductor industry, and more particularly to an apparatus in which a transfer line for refilling an ampoule and connecting the liquid source and the ampoule is mainly filled with steam.

The semiconductor industry is highly dependent on sources of ultrapure reagents. Other industries have high purity requirements, but they are hardly comparable to those in the semiconductor industry. Chemical Vapor Deposition (CVD) devices are used in many manufacturing processes in many other industries, as well as in the semiconductor industry. For example, CVD apparatus is used for the manufacture of optical waveguides. Occasionally, thin films are also formed by vapor deposition apparatus technology.

In the electronic components industry, many materials used as CVD precursors are liquid at room temperature and atmospheric pressure. In other words, the vapor pressure of the material is below atmospheric pressure at a temperature in the range of 15 ° C to 35 ° C. In order to use these materials in a CVD process, it is necessary to evaporate the material in a particular manner and introduce vapor into the process chamber where the CVD process takes place. Two processes currently widely used in the semiconductor industry are bubbling and evaporation. The bubbler uses a carrier gas (often nitrogen, helium or argon) that is introduced into the bulk liquid precursor material by bubbling. The bubble rises to the liquid level by the gravity effect, and the carrier gas exits the bubbler. Due to the vapor pressure of the precursor material, a certain amount of precursor material is carried with the carrier gas. The conveying occurs because the carrier gas is saturated with the precursor material vapor as the carrier gas exits the bubbler. The bubbler technique is most useful for high vapor pressure precursors. The second technique used is an evaporator. The evaporator is fed with a liquid feed stream and then converts the liquid feed stream into a vapor / carrier gas stream via atomization or nebulization. Evaporator techniques are most often used for precursors with very low vapor pressures.

Traditionally, these precursors in this industry are supplied in ampoules. Ampoules are generally small vessels that contain precursor materials and are made of various materials. The ampoule may be configured to convey liquid to the evaporator or as a bubbler in which carrier gas is bubbled into the liquid. Ampoules may typically be formed of quartz with breakable stems, or alternatively may be formed of stainless steel or other high quality non-contaminated metal alloys. The ampoule is transported from the manufacturer of the precursor material to the semiconductor manufacturer. The ampoule changes periodically as the material is used to maintain a reservoir of suitable precursor material. Typically, ampoules of these materials are placed very close to the CVD process chamber and the total volume of the ampoules is relatively small (up to several liters). Due to the proximity of the ampoule to the CVD process chamber, the ampoule is placed in a clean room of a semiconductor manufacturing facility.

Regardless of the type of vapor transport method used, a liquid volume of precursor material is needed near the inlet of the CVD chamber. The precursor is fed to the CVD chamber by an evaporation technique. Practical design considerations limit the amount of liquid phase volume of precursor that can be stored near the inlet of the CVD chamber. As a result, the liquid volume must be changed or refilled periodically. Changing the ampoule is a time-consuming and cumbersome task, and changing the ampoule inside a clean room is not very practical because the ampoule is typically placed inside the clean room. The time taken to change the ampoule is due to the fact that the entire manifold of the material handling component must diligently purge all remaining material before the connection between the ampoule and the manifold can be opened. A purge process is necessary for both safety and purity / contamination of the manifold.

In addition, the physical handling of bubblers filled with these reagents, which tend to be very toxic and very responsive, presents some safety problems. While performing the process with very high safety, with due care and appropriate safety precautions, some risks always exist.

Commercially available devices, such as Air Liquid's Candi system or EpiChem's EpiFill system, are liquid precursor transfer devices configured to automatically refill liquid volumes placed on the tool. These devices eliminate the need to change the ampoule in a clean room, as well as the associated downtime typically associated with ampoule changes. These devices operate by providing liquid transfer of chemical precursors and establishing communication between the liquid precursor transfer device and a tool that opens and closes the necessary supply valves. When the ampoule in the tool needs to be refilled, a signal is sent to the liquid precursor delivery device so that the tool opens the ampoule supply valve. The liquid precursor delivery device then opens its supply valve and the liquid precursor is pushed into the ampoule in the tool until the ampoule is refilled. The valve shuts off when the ampoule is filled The advantage of these liquid precursor transfer devices for liquid precursor refill devices is that the downtime of the equipment for chemical supply is eliminated, and significant cost savings can be achieved by using large source canisters of precursor material, and the required containers at the production site. Significant labor savings are achieved because the number of changes is reduced.

The inherent advantages of these devices have led to the excellent commercial success of these products. As will be apparent from the foregoing process, the tubing connecting these devices with the process tool (and associated ampoules to be refilled) remains filled with the liquid precursor during the refilling operation and during the downtime during which no refilling occurs. For certain chemicals that have particularly high reactivity characteristics, storing liquids in the line presents some problems due to safety and acceptability.

Because the distance from the device to the tool can be very large (250-500 feet or more), the amount of material stored in the line can be large. Pyrophoric and / or water reactive materials are most sensitive to these problems because there are strict rules that determine the amount of material that can be present at a given site. In addition, storing the pyrophoric liquid material in the line may affect safety because the contractor or operator may accidentally cut the line in which the liquid pyrophoric material is stored during other modifications and installations. Since the line will store a large amount of material, this can make it difficult to handle ignition on site. For spontaneous pyrophoric and water responsive trimethylaluminum, the problem is associated with defects in the lines and the resulting fire. That is, the initiation of the sprinkler device will further exacerbate the risk of fire / explosion.

An obvious solution to the problems associated with the liquid stored in the line is to refill and empty the line every time the ampoule needs to refill without storing the liquid in the line. The difficulty of this approach is that the "push back" of the liquid into the source container will not be tolerated due to potential contamination of the material. EpiFill devices work this way.

Another solution for sending out to discard material in the line would be very expensive because the liquid CVD precursor material is very expensive, sometimes more than $ 50 / g.

Thus, due to various drawbacks in current methodologies for solving these problems, there is a need in the art to develop more economical and safe solutions.

BACKGROUND OF THE INVENTION The present invention relates generally to liquid precursor refill apparatus of the type used in the semiconductor industry, and more particularly to an apparatus in which a transfer line for refilling an ampoule and connecting the liquid source and the ampoule is mainly filled with steam.

The present invention is configured to reduce risk, improve the efficiency of the refill process, reduce the defective rate as well as improve the quality of the product. These and other objects are achieved by providing a device that eliminates the need to replace the bubbler or to refill the bubbler manually. The bubbler is automatically maintained between the minimum and maximum levels, providing all the advantages of current liquid precursor transfer devices without the presence of any liquid in the line connecting the transfer device and the tool. All of this is achieved with refill reservoirs that use unique and important process steps and devices to prevent contamination and ensure safety. Accordingly, one aspect of the present invention is to provide an apparatus or the like for automatically refilling a bubbler used as a vapor conveying apparatus without maintaining a large amount of liquid precursor in the conveying line between fillings.

The present invention also provides the advantage that the line between the remote precursor reservoir and the ampoule in the tool is never filled with liquid. Bubblers and evaporators are used in the remote precursor reservoir cabinets and this vapor / carrier gas mixture is delivered to the tool. Heat transfer means liquefy or solidify the CVD precursor in the ampoule in the tool to provide a material such as that typically supplied to the process tool. A further advantage of this approach is that the bubbling device can provide a single partial distillation step and can actually improve the purity of the material delivered to the process chamber.

Another advantage of this approach is that the CVD precursor can be locally condensed and distributed to the end user in very small amounts for spiking applications. Spike techniques are used in some semiconductor manufacturing facilities to maintain a very constant mass of precursors in ampoules or bubblers during all processes and to ensure that liquid levels do not substantially vary. Maintaining a constant liquid level in the ampoule or bubbler maintains the thermal mass of the liquid in the conveying device, so that the temperature change that occurs due to the evaporation process decreases over time. The apparatus described above can respond to requests for small amounts of liquid CVD precursors at much faster response rates.

One aspect of the invention includes a method of providing a CVD precursor to a main vapor transfer device. The transfer method of the present invention includes maintaining a supply of liquid CVD precursors in a remote precursor reservoir. This liquid CVD precursor then passes through evaporation means, thereby producing a vapor phase CVD precursor. This vapor phase CVD precursor is then periodically delivered to the heat transfer means by a transfer line. This gaseous CVD precursor then passes through a heat transfer water pipe, producing a liquid or solid CVD precursor. If the precursor is a solid phase CVD precursor, heat transfer means are subsequently used to change the CVD precursor into a liquid phase. This liquid CVD precursor is then delivered to a near field precursor reservoir. The pressure in the transfer line is maintained by a constant vapor between the periodic delivery of the vapor phase CVD precursor.

Another aspect of the invention includes an apparatus for providing a CVD precursor to a main vapor transport apparatus. The apparatus of the present invention includes a remote CVD precursor source. This remote CVD precursor source includes a remote precursor reservoir and an auxiliary vapor transfer device. The apparatus of the present invention also includes a near field CVD precursor source. This near field CVD precursor source comprises heat transfer means and a near field precursor reservoir. Also included is a transfer line connecting the auxiliary steam transfer device to the heat transfer means.

The invention will be understood by reference to the following description in conjunction with the accompanying drawings.

1 is a diagram of an exemplary embodiment of the present invention,

2 is a diagram of an exemplary embodiment of the present invention showing a plurality of sequences of operations.

In one embodiment of the present invention, a method of supplying a CVD precursor to a main vapor transport apparatus is provided. The transfer method of the present invention includes maintaining a supply of liquid CVD precursors in a remote precursor reservoir. This liquid CVD precursor then passes through evaporation means to produce a vapor phase CVD precursor. Most often, the vapor phase CVD precursor will be a mixture of CVD precursor with an evaporating gas such as N ₂ , Ar or He. This vapor phase CVD precursor is then periodically delivered to the heat transfer means by a transfer line, which is typically disposed near the main vapor transfer means of the CVD tool. This gaseous CVD precursor then passes through heat transfer means to produce a liquid CVD precursor. This liquid CVD precursor is then delivered to a near field precursor reservoir. The pressure in the transfer line is maintained by a constant vapor pressure between the delivery of these periodic vapor phase CVD precursors.

In another embodiment of the present invention, an apparatus for supplying a CVD precursor to a main vapor transport apparatus is provided. The apparatus of the present invention includes a remote CVD precursor source. This remote CVD precursor source includes a remote precursor reservoir and an auxiliary vapor transfer device. The apparatus of the present invention also includes a near field CVD precursor source. This near field CVD precursor source comprises heat transfer means and a near field precursor reservoir. A transfer line is included which connects the auxiliary steam transfer device to the heat transfer means.

1, an exemplary embodiment of a CVD precursor transfer device 100 according to the present invention is shown. The CVD precursor transfer device 100 includes an auxiliary device 200 and a main device 300. The auxiliary device 200 includes a remote precursor reservoir 210 and an auxiliary vapor transfer device 220. The main apparatus 300 comprises a heat transfer means 310 and a near field precursor reservoir 320. The auxiliary device 200 is in fluid communication with the main device 300 by the transfer line 400.

In one preferred embodiment, the first pressurizing means 215 maintains a first pressure in the remote precursor reservoir 210. The second pressurizing means 225 maintains a second pressure in the auxiliary steam transport device. When the first pressure is greater than the second pressure, delivery of the liquid CVD precursor from the remote precursor reservoir 210 to the auxiliary vapor transfer device 220 via the delivery line 250 is possible. The first pressurizing means 215 or the second pressurizing means 225 may be provided by a compressed inert gas source. Liquid CVD precursors may be spontaneously flammable and / or moisture responsive. The liquid CVD precursor may be trimethyl aluminum, trimethyl gallium, triethyl gallium, diethyl zinc or dimethyl zinc. The inert gas can be nitrogen, helium or argon.

In another embodiment, auxiliary vapor transfer device 220 may include heating element 270 to increase the temperature of the liquid CVD precursor to increase the vapor concentration in the carrier gas. Heating element 270 may increase the temperature of the liquid CVD bulb to a first temperature above ambient temperature. The ambient temperature may be any temperature between 15 ° C and 35 ° C. The ambient temperature may be 25 ° C. This first temperature may be 30 ℃ to 50 ℃. This first temperature may be 40 ° C.

The auxiliary steam delivery device 220 may be an evaporator or a bubbler. When solid phase CVD precursor material is used, the second vapor transport apparatus 220 may be a sublimation apparatus. If a solid phase CVD precursor device is used, the solid phase CVD precursor may be trimethyl indium.

In one preferred embodiment, the auxiliary steam delivery device 220 is a bubbler. The carrier gas is introduced into the second vapor conveying device by the second pressurizing means 225. The carrier gas may be an inert gas. The carrier gas may be helium, nitrogen or argon. The carrier gas may be introduced at or near the bottom of the liquid volume of the CVD in the auxiliary vapor transport apparatus. Due to the vapor pressure of the liquid CVD precursor, the carrier gas is saturated by a certain amount of the CVD precursor, so that the CVD precursor is carried with the carrier gas when the carrier gas exits the bubbler.

Bubbler technology is most useful for precursors with high vapor pressure. Evaporator technology is most useful for precursors with very low vapor pressures.

After the CVD precursor is evaporated, it is introduced into the transfer line 400. The transfer line 400 may comprise either a carrier gas or an evaporated CVD precursor, or may include only an evaporated CVD precursor. The transfer line 400 will not contain any liquid phase. In one embodiment, the transfer line 400 is long enough to allow undesired heat transfer to the surroundings, such that when there is an unwanted liquid phase in the transfer line 400, the liquid removal apparatus may According to the periodic installation, it can be ensured that no liquid phase remains in the transfer line 400. The liquid removal device may be a trap, a manual valve or any device known to those skilled in the art. The transfer line 400 may be heated by the use of heat tracing if necessary. The transfer line 400 may be configured as a thermally insulating double wall containment line where the annular region is vacuum if possible.

Thereafter, the evaporated CVD precursor is transferred from the transfer line 400 to the near field precursor reservoir 320. The near precursor reservoir 320 includes heat transfer means 310. In the heat transfer means 310, the evaporated CVD precursor undergoes a phase change to the liquid phase. Any carrier gas that may be present will remain gaseous without undergoing this phase change. The heat transfer means 310 may comprise an exhaust port 330 which allows the carrier gas to escape with any other non-condensed gas. At this time, the CVD precursor went through a single partial distillation step and the purity of the CVD precursor was improved. The heat transfer means 310 can be any device known to those skilled in the art. The heat transfer means 310 may be a Peltier cooler. Exhaust port 330 may include cleaning means 335. The cleaning means 335 may be a dry adsorbent.

The liquid storage region of the heat transfer means 310 may function as the near precursor reservoir 320. In another embodiment, the liquid CVD precursor may be transferred from the heat transfer means 310 to a separate near field precursor reservoir 320. The near-field precursor reservoir 320 may be an ampoule of the main vapor delivery device 500. The near-field precursor reservoir 320 may supply an ampoule of the main vapor transport apparatus 500.

In a preferred embodiment, the near field precursor reservoir 320 may be provided with a level sensing means 325. Once the liquid CVD precursor level in the near precursor reservoir 320 reaches the first predetermined set point, the flow control means 410 in the transfer line 400 can be opened. This will allow additional evaporated CVD precursor to flow through the condenser 310, thereby increasing the level of the liquid CVD precursor in the near precursor reservoir 320. Once the level of the liquid CVD precursor in the near precursor reservoir 320 reaches a second predetermined set point, the flow control means 410 in the transfer line 400 can be closed.

In another embodiment, the evaporated CVD precursor is delivered from the transfer line 400 to the near field precursor reservoir 320. The near precursor reservoir 320 includes heat transfer means 310. In the heat transfer means 310, the temperature of the evaporated CVD precursor is reduced to the second temperature, and the CVD precursor phase changes into a solid phase. One advantage due to the reduced temperature of the evaporated CVD precursor to such a low first temperature is that it minimizes the loss of the CVD precursor incorporated into the carrier gas and evacuated. The lower this second temperature, the smaller the loss of unwanted CVD precursors. This second temperature may be below ambient temperature. The ambient temperature is any temperature between 15 ° C. and 35 ° C., preferably less than 20 ° C. This second temperature may be less than 16 ° C.

Any carrier gas that may be present will remain in the gas phase without undergoing this phase change. The heat transfer means 310 may comprise an exhaust port 330 which allows the carrier gas to escape with any other non-condensed gas. The heat transfer means 310 can be any device known to those skilled in the art. The heat transfer means 310 may be a Peltier cooler. Exhaust port 330 may include cleaning means 335. The cleaning means 335 may be a dry adsorbent.

The storage region of the heat transfer means 310 may function as the near precursor reservoir 320. In one embodiment, the heat transfer means 310 may heat the solid phase CVD precursor until the solid phase CVD precursor phase changes into a liquid phase. In another embodiment, the liquid CVD precursor may be transferred from the heat transfer means 310 to a separate near field precursor reservoir 320. The near-field precursor reservoir 320 may be an ampoule of the main vapor delivery device 500. The near-field precursor reservoir 320 may supply an ampoule of the main vapor transport apparatus 500.

Referring to FIG. 2, in the preferred embodiment, the auxiliary device 200 may be composed of two or more auxiliary steam transfer devices. The first auxiliary steam transfer device 280 may be installed in the first delivery line 450. The second auxiliary steam transfer device 290 may be installed in the second delivery line 460. The first auxiliary steam transport apparatus 280 may include a first level sensing means 470, and the second auxiliary steam transport apparatus 290 may include a second level sensing means 480. The first level detecting means 270 and the second level detecting means 480 may communicate with the automatic switching means 600. The first level sensing means 470 must detect a sufficiently low level of liquid CVD precursor in the first auxiliary vapor transport apparatus 28, and the automatic switching means 600 is configured to detect the second auxiliary vapor in the first auxiliary vapor transport apparatus 280. Switching to vapor transfer device 290 will allow continuous supply of liquid CVD precursor to main device 300. The automatic switching means 600 can be any means known to those skilled in the art.

Exemplary embodiments of the invention have been described above. The invention can be variously modified and can have alternative forms, and specific embodiments of the invention have been shown by way of example in the drawings and are described in detail herein. However, the description of specific embodiments herein does not limit the invention to the specific forms disclosed, but it is intended that the invention cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. It should be understood that it includes.

It will of course be understood that in order to achieve the developer's specific goals, such as complying with system-specific and business-related regulations that vary from device to device, certain such practical embodiments must be made and specific decisions regarding a number of devices must be made. In addition, while such development efforts may be complex and time consuming, it will nevertheless be understood that they are routine attempts to those skilled in the art having the benefit of this disclosure.

Claims (26)

An apparatus for supplying a CVD precursor to a main vapor deposition apparatus. A remote CVD precursor source comprising a remote precursor reservoir, an auxiliary vapor transfer device, A near field CVD precursor source comprising heat transfer means, a near field precursor reservoir, and A transfer line connecting said auxiliary steam transfer device to a heat transfer means CVD precursor supply apparatus comprising a. The apparatus of claim 1, wherein the auxiliary vapor transfer device is selected from the group consisting of an evaporator, a bubbler, and a solid sublimation device. The CVD precursor supply apparatus of claim 1, wherein the auxiliary vapor transport apparatus is a bubbler. The apparatus of claim 1, wherein the auxiliary vapor transport apparatus further comprises a heating element. The CVD precursor supply apparatus of claim 1, wherein the auxiliary vapor transport apparatus further comprises a first auxiliary vapor transport apparatus, a second auxiliary steam transport apparatus, and an automatic switching means. The apparatus of claim 1, wherein the CVD precursor is spontaneously flammable, moisture responsive, or spontaneously flammable and moisture responsive. The apparatus of claim 1, wherein the CVD precursor is selected from the group consisting of trimethyl aluminum, trimethyl gallium, triethyl gallium, diethyl zinc and dimethyl zinc. The apparatus of claim 1, wherein the transfer line delivers the carrier gas and the evaporated CVD precursor without the presence of liquid. The apparatus of claim 1, wherein the near precursor reservoir comprises an ampoule of a bubbler device. The CVD precursor supply apparatus of claim 1, wherein the near precursor reservoir is supplied to an ampoule of a bubbler apparatus. The apparatus of claim 1, wherein the near precursor reservoir further comprises level sensing means, the transfer line further comprises flow control means, and the level sensing means interfaces with flow control means. A method of supplying a CVD precursor to a main vapor transport device, a) maintaining a feed of liquid CVD precursor in a remote precursor reservoir, b) passing said liquid CVD precursor through evaporation means to produce a vapor phase CVD precursor; c) delivering said vapor phase CVD precursor periodically through a transfer line to a heat transfer means; d) passing said vapor phase CVD precursor through heat transfer means to produce liquid phase CVD; e) delivering the liquid CVD precursor to a near field precursor reservoir, and f) maintaining a transfer line at vapor pressure between the periodic delivery of said vapor phase CVD precursor CVD precursor supply method comprising a. 13. The apparatus according to claim 12, further comprising a plurality of evaporation means and automatic switching means, wherein step b) comprises a selected one of the plurality of evaporation means such that delivery of the CVD precursor evaporated in the transfer line is maintained. And if the evaporation means of deplete, switching to the newly selected one of the plurality of evaporation means from the evaporation means. 13. The method of claim 12, wherein said evaporation means is selected from the group consisting of an evaporator and a bubbler. 13. The method of claim 12, wherein said evaporation means is a bubbler. 13. The method of claim 12, wherein the transfer line delivers a carrier gas and a vapor phase CVD precursor without the presence of liquid. 13. The method of claim 12, wherein the near precursor reservoir comprises an ampoule of a bubbler device. 13. The method of claim 12, wherein the near precursor reservoir is supplied to an ampoule of a bubbler device. 13. The method of claim 12, wherein said near field precursor reservoir further comprises level sensing means, said transfer line further comprises flow control means, said level sensing means interfacing with flow control means. A method of supplying a CVD precursor to a main vapor transport device, a) maintaining a feed of liquid CVD precursor in a remote precursor reservoir, b) passing said liquid CVD precursor through evaporation means to produce a vapor phase CVD precursor; c) delivering said vapor phase CVD precursor periodically through a transfer line to a heat transfer means; d) passing said vapor phase CVD precursor through heat transfer means to produce a solid phase CVD precursor. CVD precursor supply method comprising a. 21. The method of claim 20, wherein said evaporation means is selected from the group consisting of an evaporator and a bubbler. 21. The method of claim 20, wherein said evaporation means is a bubbler. The apparatus of claim 20, wherein the transfer line delivers a carrier gas and a gaseous CVD precursor without the presence of liquid. The method of claim 20, a) heating a solid phase CVD precursor with the heat transfer means to generate a liquid phase CVD precursor; b) delivering the liquid CVD precursor to a near field precursor reservoir, and c) maintaining the transfer line under vapor pressure between periodic delivery of said vapor phase CVD precursor CVD precursor supply apparatus comprising a. The CVD precursor supply apparatus of claim 24, wherein the near precursor reservoir is supplied to an ampoule of a bubbler apparatus. 25. The apparatus of claim 24, wherein said near field precursor reservoir further comprises level sensing means, said transfer line further comprises flow control means, said level sensing means interfacing with flow control means.

Images